from collections import deque
n, m = map(int, input().split())
a = list(map(int, input().split()))
e = [[] for _ in range(n)]
e2 = [[] for _ in range(n)]
for _ in range(m):
  u, v, c = map(int, input().split())
  u -= 1
  v -= 1
  c = a[v] - c
  e[u].append([v, c])
  e2[v].append(u)
flg = [0] * n
flg[-1] = 1
d = deque([n-1])
while d:
  u = d.popleft()
  for v in e2[u]:
    if flg[v]:
      continue
    flg[v] = 1
    d.append(v)
inf = 1 << 60
sat = [-inf] * n
sat[0] = a[0]
d = deque([0])
flg[0] |= 2
while d:
  u = d.popleft()
  for v, c in e[u]:
    if sat[v] < sat[u] + c:
      flg[v] |= 2
      if sat[v] == -inf:
        d.append(v)
      sat[v] = sat[u] + c
sat2 = sat[:]
for u in range(n):
  for v, c in e[u]:
    if sat2[v] < sat2[u] + c and flg[u] == 3:
      print("inf")
      exit()
print(sat[-1])